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 Data from the small study of the Sangamo BioSciences
therapy, known by the code name SB-728-T, were issued in the New
England Journal of Medicine, the first publication of data from a
human trial of a technology called "gene editing."
The technique is designed to disrupt a gene, CCR5, used by HIV to
infect T-cells, the white blood cells that fight viral infections. A
patient's cells are removed and processed to alter the DNA that
codes for the CCR5 receptor. The altered cells are multiplied and
tested, then infused back into the patient.
The Phase 1 trial, led by the University of Pennsylvania, enrolled
12 HIV patients. The study's main goal was safety, but it also
showed that the modified T-cells persisted and the presence of HIV
DNA decreased, the researchers said.
"It's very solid, elegant science," said Dr Anthony Fauci, director
of the National Institute of Allergy and Infectious Diseases. "There
is a strong suggestion that cells that are generated are less
susceptible to dying."
Sangamo plans to release more trial results this week in Boston at
the Conference on Retroviruses and Opportunistic Infections. It will
also discuss strategies to improve patient outcomes.
The gene editing technique seeks to mimic the resistance to HIV
observed in the small number of people who have inherited CCR5
mutations from both parents. A patient in the trial who carried a
naturally occurring mutation in one copy of the CCR5 gene saw the
presence of HIV drop to undetectable levels.
"The target we are going after, CCR5, is the most advanced and most
promising approach for a functional cure for HIV," said Sangamo
Chief Executive Officer Edward Lanphier.
The human immunodeficiency virus, or HIV, surfaced more than 30
years ago and now infects more than 34 million worldwide. Prevention
measures have helped check its spread, while early detection and new
antiretroviral drugs can control the disease for decades, meaning it
is no longer a death sentence.
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But the complexity of the virus has stymied scientists seeking a
cure. Antiviral drugs are less than ideal due to factors including
cost, side effects and drug resistance.
"You've always got this hanging over your head ... If you could get
rid of the virus completely, you could get rid of the concern," said
Jay Johnson, a trial participant and Philadelphia volunteer
coordinator who was diagnosed with HIV in 1991.
Johnson had a bad reaction to the reinfusion of his altered
immune system cells, but reported no side affects afterward. His
viral load dropped but then crept back up, prompting him to resume
antiretroviral therapy. To control his HIV infection, the
53-year-old takes two pills twice a day, an improvement over his
1990s regimen of five pills three times daily.
"Some of my new cells are being made without the CCR5 receptor and
that is promising," he said. "Becoming HIV negative would be
wonderful."
Treatment with SB-728-T in the early-stage trial was found to be
generally safe, researchers said.
Safety is key, and "they still have to do better with durability,"
Dr Fauci said. "They've got to try and get to the point where when
they stop therapy, the virus doesn't rebound."
(Reporting by Deena Beasley; editing by
Michele Gershberg and David Gregorio)
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